The RC (final test) builds of Win7 and W2008 R2 are officially available via MSDN and TechNet as of this morning (a day earlier than expected). They’ll be available to the general public next week (probably).
I said “the” release candidates. Looks like there won’t be a second RC release. If an RC lasts for around 2 months then when would MS RTM? There’s a big conference in July in New Orleans: WPC 2009. After that you have TechEd EMEA in Berlin in November.